A wide swath of the southern sky is known as the Celestial Sea — a series of constellations associated with water. All of them were created and named millennia ago, at a time when their appearance in the night sky heralded a rainy time of year.

The leading edge of that wave of watery constellations is Capricornus. It’s fairly low in the southern sky as night falls at this time of year. Its brightest stars form a wide triangle that looks like the bottom of a bikini bathing suit.

The constellation itself represents a “sea goat” — a creature with the head and shoulders of a goat and the tail of a fish. One story says it represents the god Pan, who dived into the water to save himself from a nasty monster. He transformed his lower body into a fish in the process.

Capricornus doesn’t have any particularly bright stars, so you need dark skies to pick it out. But its borders do contain an interesting deep-sky object — a globular star cluster known as M30.

It’s about 30,000 light-years away, and it’s a ball of stars that spans about a hundred light-years. Its stars are among the oldest in the galaxy — billions of years older than the Sun. Such stars are all small and faint. So even though M30 contains more than a hundred thousand stars, you need binoculars to see it.

To give it a try, scan to the lower left of the constellation’s pattern of bright stars — the edge of the great Celestial Sea.